Different types of blood collection procedures exist, including manual collection of whole blood from healthy donors through blood drives, donor visits to blood centers or hospitals and the like. In typical manual collection, whole blood is collected by simply flowing it, under the force of gravity and venous pressure, from the vein of the donor into a collection container. The amount of whole blood drawn is typically a “unit,” which is about 450 to 550 mL.
Collection may employ a pre-assembled arrangement of tubing and containers or bags, including a flexible plastic primary container or bag for receiving a unit of whole blood from a donor and one or more “satellite” containers or bags. The blood may first be collected in the primary container, which also contains an anticoagulant (typically containing sodium citrate, phosphate and dextrose-often referred to as CPD). A preservative (often called an “additive solution” or AS, and commonly containing a saline, adenine and glucose medium-which is referred to as SAG) may be included as part of a larger assembly of containers and tubes that are used in processing after the blood is collected.
After collection of a unit of whole blood, the unit of whole blood, with connected tubing and containers, may be transported to a blood component processing laboratory, commonly referred to as a “back lab,” for further processing. Further processing may entail loading the primary container and associated tubing and satellite containers into a centrifuge to separate the whole blood into components such as concentrated red cells and platelet-rich or platelet-poor plasma. These components are then manually expressed from the primary container into other pre-connected satellite containers, and may again be centrifuged to separate the platelets from plasma. Subsequently, the blood components may be leukoreduced by filtration for further processing or storage. The process may be time-consuming, labor intensive, and subject to possible human error.
Blood banks and transfusion centers may also perform the task of “cell washing,” which removes and/or replaces the liquid medium (or a part thereof) in which the cells are suspended, to concentrate or further concentrate cells in a liquid medium, and/or to purify a cell suspension by the removal of unwanted cellular or other material.
Cell washing systems may involve centrifugation of a cell-suspension, decanting of the supernatant, re-suspension of concentrated cells in new media, and possible repetition of these steps until the cells of the suspension are provided at an adequately high or otherwise desirable concentration. Centrifugal separators used in the processing of blood and blood components may be used in such cell-washing methods.
Blood separation apparatus and procedures may employ a separation membrane to separate blood components instead of a centrifuge. This type of device includes relatively rotating surfaces, at least one or which carries a porous membrane. The device may have an outer stationary housing and an internal spinning rotor covered by a porous membrane.